Rotary multi-contact switch



y 1957 J. STOECKLIN 2,794,080

- ROTARY MULTI-CONTACT SWITCH Filed May 20, 1955 INVENT OR ATTORNEY 5United States Patent ROTARY MULTLCGNTACT SWITCH Josef Stoecklin,Ennetbaden, Switzerland, assignor to Aktiengeselischaft Brown, Bovcri &.Cie., Baden, Switzerland, a joint-stock company Appiication May 20,1955, Serial No. 509,900

Claims priority, appiication Switzerland February 16,1955

1 Claim. (Cl. 200-6) In electrical circuits one often faces the problemof effecting circuit changes without interrupting the circuit. Thisproblem arises, among other instruments, in the case of protectiverelays for current transformers where it is necessary to switch from onetap to another on the secondary winding without breaking the circuit inorder to select a desired relay-response current. One known method foreifecting this result lies in the use of plug-socket strips forprotective relays, which are constructed in such manner that the circuitwill be bridged whenever a plug is being pulled out. Another methodutilizes screw-plugs which are inserted into the desired tap. Whenchanging over to another tap it is necessary to screw a second plug intothe tap desired before the first plug can be removed in order that thetap change can be made without interrupting the transformer secondarycircuit. However, these methods are not only cumbersome with respect toconstruction and service but also require excessive space.

The principal object of the present invention is to provide an improveddevice for switching from one contact to another in changing taps on thesecondary of a current transformer without interrupting the secondarycircuit. This objective is attained by means of an improved rotaryswitch comprising one rotary arm and contact thereon adapted to makesuccessive engagement with each of a plurality of stationary contactsarranged in a generally circular array, the stationary contacts being soconstructed that the rotary contact engages the next contact in theseries before disengaging the one with which it has been in contact orengaged. Consequently a circuit is always established between the rotarycontact and one of the stationary contacts notwithstanding the fact thatthe rotary contact shifts from one to another of the stationarycontacts. Actually when passing from one to another of the stationarycontacts the rotary contact simultaneously engages the adjacent endportions of adjacent stationary contacts thus assuring continuity of thesecondary circuit of the current transformer.

A more particular object of the invention is to provide a rotarymulti-contact point switch comprising a rotary contact adapted to makesuccessive engagement with each of a plurality of stationary contactbars arranged generally in a circular array about the center of rotationof the rotary contact, the adjacent ends of adjacent bars beingoverlapped as related to the path travelled by the rotary contact sothat the latter will, for a brief period, in passing between adjacentcontacts be engaged simultaneously with those adjacent overlapping barends.

In the preferred embodiment of the invention to be described thestationary contact bars are straight and each bar is provided with acentrally located notch with sloping sides to receive the rotarycontact. Also, adjacent contact bars are located at an angle to eachother and with the adjacent ends of adjacent bars laterally overlappedwith respect to the path of travel of the rotary contact.

In the drawings which illustrate a preferred form of the invention, Fig.1 is a front elevation of the rotary 2,794,080 Patented May 28, 1957 2switch, while Fig. 2 is a vertical section taken on line 2-2 of Fig. 1.

With reference now to the drawings the body of the switch is seen to becomprised of a support 10 which is of insulating material and preferablymade from pressed laminations of sheets of insulating material. Thestationary contacts are indicated at 11 and these are seen to beconstituted at their contact faces by bars 12 each having a centrallylocated recess 13 with sloping sides so as to permit the rotary contactmember 14 to more easily move into and out of the recess. Each of thestationary contacts includes a stem portion 15 extending through thesupport 10 and which terminates in a lug 16 by which to make a solderedconnection with the conductor end. It is also possible to press the bars12 into the face of the laminated insulating support plate 10 at thetime the plate is manufactured.

As clearly indicated in Fig. l, the stationary contact bars 12 arearranged in a generally circular array about the center of rotation ofthe rotary contact member 14. The adjacent end portions 12:: of thecontact bars are laterally overlapped as regards the path of rotation ofcontact member 14 to the end that contact member 14 simultaneouslyengages such end portions for a brief period when switching from one toan adjacent stationary contact. In this manner, circuit continuity isalways maintained between the rotary contact member 14 and at least oneof the stationary contact members or bars 12. It will also be noted thateach of the stationary contact bars 12 makes, or is set at, an obliqueangle to its adjacent bar and that the bars form an angle a with thetangent to the circle.

The rotary contact member 14 constitutes the outer end of an arm 17which is secured at its inner end to a spindle 18 having a knob 19 forease in turning by hand. Spindle 18 is journalled in a bushing sleeve 20secured within an opening extending through plate 10. A spring 21 islocated on spindle 18 at the side of plate 10 opposite that on which therotary contact member 14 is located and the spring is retained inposition on the spindle and under compression by means of a washer 22and pin 23 which passes transversely through the outer end of thespindle. One end of the spring 21 bears against the washer 22 and theother end bears against the back face of plate 10. The result of sucharrangement is to bias spindle 18 and hence arm 17 and contact member 14into engagement with the stationary contacts 12. As spindle 18 isrotated to move the rotary contact member 14 from one to another of thestationary contact bars 12, the spring 21 permits suflicient axialdisplacement of the spindle to enable the rotary contact member 14 tomove out of and into the recesses 13 in the contact bars 12. A screw 24at the end of spindle 18 provides a means for connecting a conductor endto the spindle and hence to the rotary contact member 14, it beingassumed of course that all parts of the switch excepting the mountingplate 10 are made of electrically conductive material.

In conclusion it will thus be evident that the invention makes itpossible to change over from one contact to another in a rotary switchdevice without ever interrupting the circuit between the rotary contactmember and the array of stationary contacts. Also the obliquepositioning of adjacent stationary contacts 12 also has the additionaladvantage of establishing a wider leakage path between adjacentcontacts. Moreover, while a preferred embodiment of the invention hasbeen described, it is to be understood that various minor changes in theconstruction and arrangement of parts may be made without, however,departing from the spirit and scope of the invention as defined in theappended claim.

I claim:

In a rotary switch the combination comprising a sup- 3 port plate ofinsulating material, a rotary contact mem ber mounted on said support, aplurality of flat elongated stationary contact members mounted on saidsupport in a substantially arcuate array about the center of rotation ofsaid rotary contact member, the contact ends of said stationary contactmembers engaged by said rotary contact member being recessed betweentheir narrow sides for engagement in succession by said rotary contactmember, adjacent recessed ends of adjacent ones of saidstationarycontact members being laterally and obliquely overlapped so that saidrotary contact member in moving from one to another of said stationarycontact members simultaneously and temporarily engages said overlappedend portions thereby maintaining temporary circuit continuity betweensaid rotary contact member and adjacent 15 2664473 ,4 ones of saidstationary contact members, said stationary contact members extendingthrough said support plate and including connection means such as lugsat the opposite ends thereof.

References Cited in the file of this patent UNITED STATES PATENTS734,438 Skinner July 21, 1903 825,838 Jacobson July 10, 1906 1,395,886Amerton Nov. 1, 1921 1,498,817 Smith June 24, 1924 1,624,391 ClausenApr. 12, 1927 2,454,295 Verkuil Nov. 23, 1948 Brown w Dec. 29, 1953

